REFLECTOR: Running LOP -- Climbing or Cruising

[Scott Derrick]

 >-------- Original Message --------
 >Subject: Re: REFLECTOR: Running LOP -- Climbing or Cruising
 >From: Brian Michalk <michalk at awpi.com>I know this doesn't directly 
answer the LOP operation.  We can either go LOP or ROP.  To run at peak 
EGT is to run at peak combustion temps, heating up >the cylinders, 
raising the charge temps.  If one is able to get all of the cylinder 
temperature profiles to line up exactly, then there's no thermodynamic 
operating difference if one runs 25 ROP or 25 >LOP.  They are identical 
... or almost identical in that the ROP regime makes an almost 
insignificant more power.



Just to add a bit of clarity, running 25 ROP or 25 LOP is running at 
basically the same temp, or thermodynamically as Brian put it.

But, it is greatly different in regards to what is happening in the 
engine in all other regards. I've attached a picture to illustrate one 
of the fundamental
differences between the two.  Its tough to figure this out without the 
article but the purple line is 75 ROP, peak pressures are close to TDC 
exerting maximum force when you don't want it, the blue line is 50 LOP, 
almost a full 10 degrees further away from TDC, thus exerting more of 
that force to turning the crankshaft instead of pushing your crankcase 
apart!

Here's a link to the article I smurfed this image from. Its a great read 
and very revealing.

http://www.avweb.com/news/pelican/182104-1.html

Scott
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